Breaking

Anthropic Ships Claude Sonnet 5 With 1M Context and Cheaper Agent Runs

June 30, 2026 at 13:37 EDT

Foundation Models
AI Agents
Software Dev & Coding

Anthropic released Claude Sonnet 5, the newest model in its Claude family, on June 30, 2026. Priced in the Sonnet tier yet aimed at approaching the flagship Opus 4.8, it leans heavily into autonomous, tool-using "agentic" workloads.

June 30 · Anthropic · Unconfirmed Leak

"Claude Sonnet 5" Surfaces on OpenRouter Ahead of Any Official Word

A model ID (claude-sonnet-5-20260630) appeared on an aggregation platform and inside the Claude Code CLI binary — pointing to an imminent release. Anthropic has made no announcement; all figures below are rumor-stage.

Token context window (leaked, both tiers)

Jan 2026

Reported knowledge cutoff

v2.1.197

Claude Code CLI binary where the ID was spotted

Leaked output price per 1M tokens — "Opus-class at Sonnet pricing"

Output rate compared across tiers (lower = cheaper). Figures unconfirmed.

$10

Sonnet 5
promo

$15

Sonnet 5
standard

$25

Sonnet 5
1M-context

$50

Opus 4.8
(reference)

Even at the 1M-context tier, the leaked Sonnet 5 output rate is half the Opus 4.8 price — and the promo tier is 1/5 of it.

Why developers are excited

Opus-level performance at Sonnet pricing could reshape coding on large projects
1M-token context plus low cost is strong for agent use cases

Reasons for caution

Lineup still lists only up to Sonnet 4.6 — no Sonnet 5 entry
Pricing and performance unverified; a quality or regulatory delay is possible
The "Claude Science" app shipped, but the model itself did not

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